The Rhaetian Railway Be 4/4 is a class of 11 kV 16.7 Hz AC metre gauge railcars operating under the traffic numbers 511–516 on the so-called core network of the Rhaetian Railway (RhB), which is the main railway network in the Canton of Graubünden, Switzerland. The class is named under the Swiss locomotive and railcar classification system. According to that system, Be 4/4 denotes an electric railcar with second class compartments, and a total of four axles, all of which are drive axles. The Be 4/4 vehicles normally operate as part of a three or four car train, in combination with one or two intermediate cars (B) and a driving car (ABt). History In the 1960s, the Rhaetian Railway was exposed to steadily rising passenger numbers and therefore increasing demands on its rolling stock. In particular, passenger expectations of rolling stock had altered. These changes led the Rhaetian Railway to carry out detailed studies as to what new rolling stock should be acquired. The studies revealed, amongst other things, that there was a need for a contemporary vehicle concept to serve commuter traffic around Chur. The Rhaetian Railway therefore decided, at the end of October 1968, to order four modern three car commuter trains. These could be used not only for Chur's commuter traffic, but also for special sports trains. In 1971, the three manufacturers of the power cars, FFA (railcar bodies), SIG (bogies), and SAAS (electrical equipment), delivered the first four power cars (numbers 511–514) to the Rhaetian Railway. These vehicles were Switzerland's first series production units with continuous electronic power control (phase control thyristors). Simultaneously, the Rhaetian Railway placed the matching intermediate cars (B 2411–2414) and driving cars (ABDt 1711–1714) into service, so that four three car commuter trains could be formed. In contrast with the rest of the Rhaetian Railway's rolling stock, the Be 4/4 commuter trains are fitted with automatic couplings and air brakes; mixed use of the vehicles with other rolling stock is therefore not possible. In 1979, the Rhaetian Railway acquired two practically identical three car trains with traffic numbers ending in 15 and 16. After four additional intermediate cars (B 2417–2420) joined the fleet in 1988, four car trains could also be operated. From 1994, the vehicles went through an extensive refit program, during which the electrical equipment was completely renewed, apart from the traction motors. Technical details The Be 4/4 vehicles were